This invention mainly relates to a vibration-isolating device used to support a vibration generating source such as vehicle engine for the purpose of vibration isolation.
A liquid-in vibration isolator has been known as a mount supporting a vibration generating source such as vehicle engine so as not to transmit its vibration to a vehicle body (for example, JP-A-9-89037, JP-A-10-9330).
The vibration isolator of such type is configured so that a cylindrical body fitting attached and fixed to the support side such as vehicle body frame and an upper side attachment fitting attached to the side of the vibration generator such as engine are connected via a thick vibration isolating substrate made of a rubber material with external contour in the form of nearly truncated cone, a diaphragm is further disposed at the lower side of the body fitting opposite to the vibration isolating substrate, there are liquid-in chambers between the vibration isolating substrate and the diaphragm, the liquid-in chambers are divided into two liquid chambers on the side of the vibration isolating substrate and the diaphragm by means of a partition member, both liquid chambers are passed through by an orifice, the vibration damping and vibration isolating functions are fulfilled by the liquid flowing effect between both liquid chambers produced by the orifice and the vibration suppressing effect of the vibration isolating substrate.
The vibration isolator of this kind provides a stopper mechanism to restrain the displacement of more than the predetermined level of the upper side attachment fitting when the vibration isolating substrate is deformed due to vibration of engine and the like and the upper side attachment fitting moves in the up-and-down direction and the fore-and-aft and lateral direction square to the axial direction.
The stopper mechanism is constructed so that a stopper flange projecting radially is provided for the upper side attachment fitting, a cylindrical stopper fitting extending outwardly of the vibration isolating substrate above the flange is fixed to the cylindrical body fitting, the upper end of the stopper fitting is inwardly folded and formed to be located above the flange, for acting stopper function.
With the use of this stopper mechanism, in time of large displacement in the upward direction or square to the axial direction (fore-and-aft or lateral direction) accompanied by vibration, the stopper flange abuts the folded extremities or the side walls in the form of an inner flange of the stopper fitting to restrain movement of the upper side attachment fitting more than a certain level, and the upper side attachment fitting is difficult to be released (falling off) when a vehicle comes into collision, etc. Thus, the stopper mechanism brings about high reliability in strength.
However, in the case of the vibration isolator of the aforementioned structure, since entire circumference of the vibration isolating substrate portion is covered with the stopper fitting, the inside of the stopper fitting is liable to be filled with radiant heat of an engine and the like so that the ambient temperature of the portion becomes higher than that of outside, whereby there is a possibility that vibration isolating substrate made up of a rubber material is cracked or torn earlier, with the result that durability is deteriorated. Further, if rainwater and the like penetrates from an opening at the upper portion of the stopper fitting, the water remains there without draining away. The water becomes rotten and is liable to cause corrosion or rust, thus there is the possibility of making the vibration isolating substrate change in quality or deteriorate.
As a means of settling these problems, it has been considered to form a notch window for drainage and ventilation on the side wall of the stopper fitting so far (for example, JP-A-8-210423). In this case, when there is only one notch window, ventilating effect cannot be obtained sufficiently, and drainage effect of penetrated rainwater and the like is not sufficient. Therefore, it is preferable that the notch window shall be formed at two opposite places.
Incidentally, the stopper fitting is caulked and secured at the lower extremities thereof as against the opening extremities of the body fitting, as roughly cylindrical shape with the notch window portion cut out. As for this caulking and securing, although the opening extremities of the body fitting are in the form of a flange of the same diameter over entire circumference, unless the opening extremities are provided with circumferentially positioning means, it is not easy to perform positioning at the time of caulking and securing, and the direction of stopper fitting against the body fitting is liable to get out of position.
For example, if the direction of the notch window of the stopper fitting must be aligned to a definite direction of fore-and-aft of the vehicle and the like with respect to the body fitting attached to the support side of the vehicle frame, etc., it is difficult to perform positioning at the time of caulking and securing, special jigs and the like are required for the positioning, and it is also highly feared that the state of fixing gets out of position.
In the state of use of the vibration isolating device, the stopper fitting abuts to the member such as bracket on a vibration generating source of the stopper fitting. However, if any load from such abutment is applied to the stopper fitting locally and repeatedly, there is a possibility that the stopper fitting gets out of position circumferentially or parts from the body fitting. In particular, since the caulked and secured portion is separated into two opposite portions when the notch window is formed at two opposite places, it is considered that such getting out-of-position and the like are liable to be occurred.
Therefore, when any notch windows are provided on the stopper fitting of the vibration isolating device, it is desired that the stopper fitting can be positioned easily and securely in regard to the opening extremities of the body fitting and that getting out-of-position and the like due to loading by stopper action can also be restrained. The present invention has an object to settle such problems.
The vibration isolating device of the present invention comprises a body fitting having a cylindrical barrel, an upper side attachment fitting disposed upward an axis center of the body fitting, a vibration isolating substrate made of a rubber material to connect both fittings, a stopper fitting fixed at an opening extremities of the body fitting and extending upwardly outside the vibration isolating substrate, its upper end portion being folded inside as a stopper portion, so that the stopper fitting acts stopper function for large displacement of the upper side attachment fitting consequent upon vibration, a notch window for drainage and ventilation being formed at least two opposite places at the lower portion of the stopper fitting, and a protrusion for circumferential positioning fitting-in and engaging with the notch windows provided at the opening extremities of the body fitting.
According to the vibration isolating device, when the stopper fitting is fixed to the opening extremities of the body fitting by, for example, a caulking fastening means, the stopper fitting can easily be positioned by fitting the notch windows at the lower portion of the stopper fitting into the protrusion for positioning on the opening extremities of the body fitting, and also restrain from circumferential movement. Thereby, the stopper fitting is accurately positioned and secured so that the notch windows thereof are in a definite direction to the body fitting.
Furthermore, in the state of use, even when the stopper fitting is loaded locally and repeatedly by the loading due to stopper action at the time of bounding, since the protrusions are fitted into and engaged with at least two opposite notch windows, it is not apprehended that the stopper fitting circumferentially gets out of position or parts from the body fitting. Therefore, proper and adequate draining and ventilating effects through at least two opposite notch windows can increase its durability.
As a securing means of the stopper fitting, normally, the opening extremities of the body fitting may be formed in the form of a flange, and the lower extremities of the stopper fitting be caulked and secured to the flanged opening extremities. Thereby, the stopper fitting can easily and accurately be positioned, and also easily be caulked and secured.
The protrusions for positioning can be produced easily by radially projecting from the edges of the flanged opening extremities. Furthermore, by making the protrusions engage with circumferential both side edges of the notch windows, the stopper fitting can be positioned circumferentially and prevented securely from getting out of position.
Furthermore, as for the vibration isolating device, it is preferable that the notch windows has an opening width in a range of angle from 50 to 70xc2x0 as viewed from an axial center of the device, and that the protrusions are formed at least both side extremities in a range corresponding to the notch windows. Thereby, draining and ventilating functions can be performed properly through the notch windows, and the stopper fitting can be positioned and also prevented from getting out of position properly.
As for the vibration isolating device, the upper side attachment fitting has a stopper flange projecting outwardly upwards the vibration isolating substrate, the stopper portion of the stopper fitting is interposed between the flange and the vibration generator fitted and secured above the flange so as to perform stopper action against vertical large displacement of the upper side attachment fitting. This allows proper stopper action.
With regard to the vibration isolating device, it is desirable, from the viewpoint of vibration damping function and vibration isolating function, that a diaphragm made of a rubber film is disposed opposite to the vibration isolating substrate at the lower side of the body fitting, that there is a liquid-in chamber between the vibration isolating substrate and the diaphragm, that the liquid-in chamber is divided into two liquid chambers at the vibration isolating substrate and the diaphragm by means of a partition member, and that both liquid chambers are connected by an orifice.